Cellular communication networks typically comprise a radio access network comprising a set of base stations, and a core network comprising nodes tasked with managing the system and routing data to and from further networks, in some networks, the radio access network comprises in addition to base stations base station controlling nodes, such as for example radio network controller, RNC, nodes in a wideband code division multiple access, WCDMA, communication system. Another example of a base station controlling node is a base station controller, BSC, controller node in a global system for mobile communications, GSM, communication system.
Communication in a cellular communications network typically traverses the network, for example where a cellular telephone is called from a landline, the call will arrive from the landline network in a gateway node comprised in the core network of the cellular network, and be routed from there to the radio access network, for delivery from a base station in the radio access network, via a radio interface, to the called cellular telephone. Likewise where a cellular telephone calls another cellular telephone of the same network, the call may be routed via the radio access network and core network to the called cellular telephone.
On the radio interface, cellular communications may use radio resources allocated to such use, wherein the networks may manage use of the radio resources so as to allow users access to the system in an optimal way. Managing the radio resources may comprise balancing availability and quality of service, since the allocated radio resources may not be sufficient to provide maximal service continually to all users. The users may be further constrained by access to energy when their cellular telephones, or more generally terminals, are battery-powered.
In some cases, use of radio resources may be optimized by terminals of a cellular communications network communicating with each other directly in the sense that they receive radio signals from each other, rather than from a base station. In other words, information may be exchanged between the terminals so that the information isn't routed via a base station, rather the information is transmitted from a first terminal and received directly from the radio interface in a second terminal.
Direct communication between terminals may use radio resources also used when communicating with a base station, or alternatively direct communication may use different radio resources. When the same radio resources are used the cellular communications network may have an interest in at least partially controlling the direct communication, since resources used in the direct communication may become unavailable for other communication in the cellular communications network. Where different resources are used, the cellular communications network may also have an interest in at least partially controlling the direct communication, for example where interference is possible with resources of the cellular communications network, or where the network wants to charge the terminals for the direct communication, or for other reasons.